Niro Soavi S.p.A
4C042E0C.DOC 4.4.6
4.4.2 PLUNGER SEALS
The lifetime of these parts is dependent on the following factors:
- Working pressure
- conditions of plungers surface;
- process temperature;
- type of product;
- machine underfeeding (not enough feeding pressure, see Section 1 –
TECHNICAL SPECIFICATIONS for reference);
- worn out parts (washers, spacers) in contact with the seals.
The life of gaskets, and in particular of plunger packings, is not covered by
guarantee and cannot be estimated beforehand; we therefore suggest you
calculate the average life of the packings in order to schedule preventive
maintenance.
To avoid situations where production has to be stopped due to missing plunger
gaskets, we suggest you schedule preventive replacement on the basis of their
expected mean life.
In high-pressure machines, check and preventive replacement of packings
should be carried out every 100÷200 hours.
Replacement is necessary when you notice leaks from the sump; the production
cycle can be allowed to go on if the leak is not too big.
Plunger gaskets in high-pressure machines must be considered as one single
seal system, in which all the components contribute to the life and efficiency of
the gasket; we therefore recommend that you replace all the support and anti-
extrusion rings during maintenance work, in order to increase the life of the
sealing system.
For the maintenace procedure and seals replacement it is necessari to
disassemble the pumping plungers, therfore follow the specific directions of
paragraph 4.4.1.
CAUTION: Before you begin with maintenance and gasket replacement
make sure all the necessary spare parts and tools are available.
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